The Effect of Decentralized Rainwater Tank System on the Reduction of Peak Runoff

1. Conventional System Localized Heavy Rain Localized Heavy Rain Floodin Urban Area Floodin Rural Area Overflowing Repeated Disaster Localized Heavy Rain Decentralized System Localized Heavy Rain Detention Infiltration & catchment facilities Infiltration & catchment facilities Reduction of flow Reduction of flow The Effect of Decentralized Rainwater Tank System on the Reduction of Peak Runoff - A case study at M village - Mooyoung Han*, Soyoon Kum*, Jeoungyoun Kim*, Jungsoo Mun** * Department of Civil and Environmental Engineering, 35-517 Seoul National University, Daehak-dong, Kwanakgu, Seoul, 151-744, Korea (E-mail: myhan@snu.ac.kr) ** Senior Researcher, Plant Business Headquarters, Lotte Engineering & Construction, Seoul, Korea Input Output Hydrograph (Channel, Outfall) Meteorological data (Precipitation, Evaporation) Water level curve (Manhole, Channel, Retention tank) Catchment data (Catchment characteristics, Infiltration) Extract data From ArcGIS Flooding level, Area (Retention tank, Weir, Orifice) Channel data (Conduit characteristics) Runoff volume velocity curve (Subcatchment, Conduit) Structure data (Retention tank, Weir, Orifice) Concept of DRMS (Decentralized Rainwater Management System) Introduction Rainfall Drainage Current measures &limitation peak flow ≫ max capacity Pipe extension Newly- Pipe laying Large scale detention pond Types of Centralization Detention basin Rainwater tank Full! Need New water management paradigm!! High cost & energy uncertain, unsustainable resident complain Time of concentration 30 min ~ hours < 10 min Building rooftop Drainage pipe < 1 ha 10 ~ 100 ha Runoff area Flow control Detention Retention Methodology Governing Equation 1. Conventional system vs DRMS 2. Modeling Process 3. Research Site Simulation 1. Runoff Mode 2. Sanitary Mode 3. Hydraulics Mode Entry conditions Boundary condition M village, Suwon city, Gyeong-gi province, Republic of Korea Results and Discussions 1. The peak flow reduction effect by number of storage 2. The peak flow reduction effect by location of storage <Method of case selection> <Method of case selection> Condition 1 : RST volume and unit (※ Total volume : 3,000㎥) Centralized Decentralized Condition 2 : Location (※ Application to real flooded area as priority) Case 5 : UWS (U-type) Case 6 : MWS-a (M1-type) Case 7 : MWS-b (M2-type) Case 8 : DWS (D –type) <Modeling results> <Modeling results> Conclusions • If rainwater tank is installed into existing urban drainage system, peak flow rate reduction effect is shown and inundation damage can be prevented. • Although total storage volume of rainwater tank is same, increment of tank number induces more peak flow rate reduction. • With disposition type of rainwater tank, peak flow rate reduction effect is change. In the case of research area, Upper-mid rainwater location is the most effect placement. This research was supported by a research fund (2Z03401) from Engineering Research Center at Seoul National University.